Combination explosionproof switch plug and receptacle



Oct. 17, 19 39. R BLOOD 2,176,290

COMBINATION EXPLOSIONPROOF SWITCH PLUG AND RECEPTACLE Filed July 14; 1936 5 Sheets-Sheet 1 wi fim ATTORNEYS Get. 17, 1939.

R. A. BLOOD COMBINATION EXPLOSIONPROOF SWITCH PLUG AND RECEPTACLE Filed July 14, 1936 3 Sheets-Sheet 2 %ZNV/EZTOR BY V ATTORNEYS,

Oct. 17, 1939. R. A. BLQOD 2,176,299

COMBINATION EXPLOSIONPROOF SWITCH PLUG AND RECEPTACLE Filed July 14, 1936 3 Sheets-Sheet 3 ATTORNEYS.

Patented Oct. 17, 1939 UNITED STATE PATENT OFFICE COMBINATION EXPLOSIONPRDOF SWITCH PLUG AND RECJEP'EACLE poration of New York Application July 14., 1936, Serial No. 90,548

12 Claims.

This invention relates in general to explosion proof electrical fittings of the plug and receptacle type. Heretofore, in order to obtain the explosion proof feature, such fittings have been constructed with a switch mounted in an enclosed housing, and means provided, in the nature of an interlock, whereby the switch could not be actuated to on position until after the plug has been moved into cooperating relationship with the receptacle, and the plug could not be withdrawn until after the switch had been actuated into the chi position. In such structures, the switch is actuated into on and off positions by a manual operation separate and distinct from the movement of the plug in and from the receptacle.

Also, where the apparatus carried smaller currents, the receptacle has been divided into two sections, the plug cooperating with the outer section and thereafter the plug and outer section moved relative to the inner section to effect contact and complete the electrical circuit.

The first structure referred to is costly and bulky, in that it requires a considerable amount of mechanism to obtain the interlocked feature, and further requires a separate operation to actuate the switch.

In the secondstructure, the advantages of a conventional switch are absent, particularly the quick make and break feature, with the result that such devices can carry only comparatively small currents without burning the contacts between the outer and inner sections of the r ceptacle. Furthermore, inasmuch as these contacts are part of the inherent structure of the device, it is difficult to renew them and new contacts must be purchased from the manufacturer of the device.

The general object of the invention is a device of the type referred to of such structure that any conventional type of switch may be employed, and is actuated into on and oii positions by movement of the plug and receptacle relative to the housing.

Anobject of the invention is an electrical fitting of the type referred to of such construction that the switch is housed in a flame tight housing and can not be actuated into on position until after the plug is moved into cooperative relationship with the receptacle.

The invention has as a further object, a construction by which the plug can not be withdrawn from the receptacle until the switch in the housing has been shifted into the off position.

The invention has as a further object, a particularly economical and, simple construction wherein the receptacle constitutes part of the (Cl. ace-50 switch actuating mechanism and is maintained at all times in flame tight relationship to the housing.

A further object is a construction by which the switch can not be actuated into the on position 5 after the plug has been removed from the receptacle.

The invention further includes structure which prevents opening of the housing while the switch is in the on position.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like char- 15 acters designate corresponding parts in all the views.

Figure l is a plan view of the switch and receptacle housing.

Figure 2 is a vertical, longitudinal section through the housing with the switch and a. portion of the receptacle in elevation.

Figure 3 is a transverse, sectional view of the housing, with the outer end of the receptacle in elevation, it being taken on lines 3-3, Figure 2.

Figure i is an elevational view of the switch and inner end of the receptacle, with the switch illustrated in the on position by dotted lines.

Figure 5 is a fragmentary, sectional view of one of the receptacle terminals, being taken approxiniately on lines 55, Figure 4.

Figure 6 is a fragmentary, sectional view of one end of the housing, taken on lines 66, Figure 2.

Figure 7 is a longitudinal, sectional view of the outer end of the housing showing the plug in 00- operating relationship to the receptacle.

Figure 8 is an end elevational view of the plug.

The invention comprises generally, a cooperating plug and receptacle, a housing, the receptacle being movably mounted inthe housing in flame tight relationship therewith, and a switch also mounted in the housing, motion transmitting means between the receptacle and the-switch, whereby the switch is actuated into on and oil? positions upon movement of the receptacle relative to the housing.

The invention further includes structure which normally maintains the receptacle in apredetermined position with the switch in the off position, and which is operable when the plug is inserted in the receptacle to permit the plug and receptacle to be moved relative to the housing to actuate the switch into on position, and means whereby the plug can not be removed from the receptacle while the switch is in on position. 6

The body or housing may be of any suitable size and form. As here shown, the housing is formed with a cylindrical central portion ID, the upper or outer end of which is threaded internally to receive the plug closure A hub |2 extends from one side of the cylindrical portion l0, and is provided with an internally threaded aperture to receive a conduit enclosing the electrical conductors of the system. The opposite side of the central portion is formed with an enlarged hub |3 in which the receptacle is mounted in a manner to be hereinafter described, and the outer end of the hub I3 is provided with a suit able closure in the nature of a spring pressed door M. The base or bottom I5 of the housing is formed with transversely extending bosses l6 which may be provided With one or more holes I? to receive mounting screws. The outer end of the cylindrical portion iii is truncated at an angle, and the axis of the hub l3 extends parallel therewith in order to facilitate insertion and removal of the plug when the fitting is mounted in a vertical position.

The hub 3 is provided with an internally threaded bore adjacent the cylindrical portion Ill, and the receptacle is cylindrical in general form and the inner portion thereof is provided with external threads complemental to the threads in .the bore of the hub |3, whereby the receptacle may be threaded into the hub, as illustrated in Figure 2. The receptacle is formed with an outer portion 23 and an inner portion 2|. Suitable terminals are mounted in the outer section 20, and are arranged to receive the contacts 22 of the plug.

The receptacle terminals here shown comprise a hexagonal member 23 inserted in an aperture formed in the outer portion 20 of the receptacle, and a bifurcated spring member 24 connected to the insert 23 by a strap 25, to one end of which the bifurcated contact receiving member 24 is secured, as by a rivet 26. The other end is provided with an aperture to receive the outer end of the insert member 23, which is swedged over the strap 25, as at 21. The insert member 23 is threaded to receive a binding screw 28. The bifurcated contact receiving member 24 is mounted in an aperture extending throughout the outer portion 20 of the receptacle.

As here shown, the plug and receptacle are provided with three contacts and terminals respectively. One contact and its complemental terminal extends radially of the plug and receptacle, and the remaining two in angular relationship to the first. One of the contacts and its complemental terminal is connected to the grounding conductor of the electrical system, and by the arrangement of the contacts and terminals just referred to, it is necessary to insert the contacts into the terminals in a predetermined cooperating relationship. The receptacle 20 may be moulded from insulating material, such as Bakelite, or the like.

The plug, as here shown, consists of a tubular metallic sleeve in which a cylindrical block of insulating material 36 is mounted. The sleeve 35, adjacent its outer end, is formed with one or more-shoulders 31, and the contact carrying block 36 is provided with complemental shoulders seating against the shoulders 31, and is retained in suchposition by a snap ring 38, see Figures '7 and 8.- The plug contacts 22 consist of outwardly extending prongs rectangular in cross section and having secured to their inner ends the conductors 39 of the. plug cable 40. The outer end of the tube 35 is provided with a suitable cable clamp 4|.

The tube 35 extends an appreciable distance beyond the outer face of the block 36, and is of such relative dimension as to be sleevable over the outer portion 20 of the receptacle, and the hub |3 of the housing is formed with a bore to receive the tube. The bore is provided with an axially extending groove 42, the inner end of which communicates with a circumferentially extending groove 43. The sleeve 35 of the plug is provided on its periphery with a boss or projection 44 which, together with the grooves 42, 43, is arranged relatively to the contacts 22 and terminals 24 to bring the contacts 22 into engagement with the terminals 24, while the projection 44 is arranged in the groove 42. The groove 42 is of such depth as to permit the plug to be moved into full cooperating relationship with the receptacle.

In order to relieve the prongs 22 of the plug from unnecessary strain during rotation of the receptacle by the plug, the receptacle may be provided with one or more radially extending bosses 46, and the end of the tube 35 with complemental recesses 41.

It will be observed, from the structure thus far described, that the receptacle is movably or rotatably mounted in the housing, and because of the threaded connection between the inner portion 2| of the receptacle and the hub l3 of the housing, the receptacle is mounted in flame tight relationship to the housing and may be so rotated by rotation of the plug when it has been inserted in the receptacle, and the projection 44 is in register with the circumferentially extending slot 43. Also, after the plug and receptacle have been rotated, the plug may not be removed from the receptacle because of the cooperating projection 44 and groove 43.

The conductors 39 are not electrically connected to the conductors in the conduit system, or the interior of the housing, by the engagement of the contacts 22 with the terminals 24, but such connection is effected by means of a switch mounted in the cylindrical portion ll) of the housing, and which is actuated into on and 011 positions by movement of the receptacle. The switch 50 may be of any conventional type. As here shown, it is of the toggle type being actuated into on and off positions by relative movement of the operating member or handle 5| and the switch 50. As here shown, the switch 50 is secured to and carried by the inner section 2| of the receptacle. The switch is mounted upon a plate 52 which, in turn, is secured to an inwardly extending projection 53 of the inner portion 2| of the receptacle, as by screws 54, see Figures 2 and 4. Rotation of the receptacle effects bodily rotation of the switch.

The bottom |5 of the housing is provided with one or more bosses 48 which carry a bridge member 55 to which is secured spaced apart members 56 extending lengthwise of the housing and engaging the handle 5| of the switch, preventing movement of the same during movement of the switch 50 upon rotation of the receptacle. The bridge member 55 may also serve as a convenient support for a terminal block 51. It will be observed that upon rotatable movement of the receptacle, bodily movement of the switch 50 is effected relative to the switch handle 5|, thus actuating the switch into on and off positions. The movement of the switch from off to on position is indicated by dotted outline Figure 4.

'It "will be-understood that the terminals 24 of the receptacle are connected to the terminals of the switch 50, as by conductors'59, and the terminals of the switch 50 connected to the terminals of the terminal block 51 as by conductors 60. After the conductors 59' have been secured to the terminals 24 of the receptacle, the'interior of the inner projectionZl of the plug is filled with suitable sealing compound which is not illustrated in Figure 2 for the sake of clarity.

To provide a further factor of safety,- means is provided for normally maintaining thereceptacle in such position that the switch is in the off position. The receptacle is provided with a notch 6| adjacent the inner end of the outer section 20, and a latch member 62 is pivotally mounted adjacent the outer end of the hub 13. The inner or free end of the latch member 62 is pressed toward the axis of the receptacle and into the notch 6| by a spring 63 which encircles the pivot pin 64, and having one end cooperating with the hub l3, and the opposite end with the latch member. 1 a As here shown, Figures 2 and 3, the latch member is bifurcated at its pivoted end, and the spring 63 mounted between the legs-65. The latch member 62 is arranged to be engaged by the outer end of the sleeve 35 of the plug and moved out of the slot 6| thereafter permitting rotation of the receptacle.

As a further factor of safety, means is provided whereby the plug closure H can not be removed from the housing while the switch is in the on position. The closure It is provided with a radially extending marginal fiange' 66 overlapping the marginal end surface of the cylindrical portion I0 surrounding the threaded opening therein. The closure H is also provided with one or more radially extending bosses 61 provided with an aperture 68 which is counterbored on the under side adjacent the marginal edge of the cylindrical body portion In.

The body is provided with a threaded aperture extending vertically through the wall of the cylindrical portion ID and communicating with the interior of the housing adjacent the inner end of the inner portion 2 [of the receptacle. A screw 69 is threaded into this aperture, and the inner end of the screw 69 engages a notch Til arranged in the inner end of the receptacle, and solocated relativelythat the screw 69 registers therewith when the receptacle is moved to actuate the switch in the OE position, as indicated in Figure 2, and at which time the outer end of the screw is flush or below the marginal face surrounding the threaded opening of the body.

In order to permit relative movement of the receptacle and housing, it is necessary to insert a suitable tool through the aperture 68 and back the screw 69 out of engagement with the notch 10, at which time the outer end of the screw on,- ters the enlarged or counterbored portion of the aperture in boss 61, thus preventing the'plug closure H from being unscrewed from the housing.

It will be apparent to those skilled in the art that any conventional type of switch may be substituted for that shown, and the switch may be rigidly mounted in the housing and the receptacle operatively connected to the handle of the switch, it being necessary only to eiiect relative movement between the switch and its handle to actuate it into on and oif positions.

The advantages of the structure described will be readily appreciated, The switch may be readily replaced through the opening of the cylindrical portionof the body, and if it isdesired, different types of switches may be installed for switches of different carrying capacities. While the structure has the advantage of a plug and receptacle device, the switch contacts are housed in a flame tight explosion proof housing and are operable with the greatest factor of saving. Also, while possessing these advantages, the structure is economically manufactured andassembled and is exceedingly convenient for the workman to install. a The housing may be installed with the receptacle and switch removed, permitting complete access to the interior of the housing for manipulation of wiring, and thereafter it is only necessary to screw the receptacle into the housing, no adjustment of a skilled worker being necessary and subsequently attaching the switch to the receptacle by two screws 54.

What I claim is:

1. In a device of the type described, the combination of a cooperating plug and receptacle, of a housing, said receptacle being mounted in-said housing and being movable relatively thereto and in flame tight relationship therewith, a switch mounted in the housing, means cooperable with said receptacle and switch to effect actuation of the switch into on and off positions upon movement of the receptacle relative to the housing, means normally securing the receptacle from such relative movement and being operable upon movement of the plug into cooperating relationship to the receptacle to permit movement of the receptacle.

2. In a device of the type described, the combination of a cooperating plug and receptacle, of a housing, said receptacle being movably mounted in said housing in flame tight relationship therewith, a switch mounted in the housing, means cooperable with said receptacle and switch to efiect actuation of the switch into on and off positions upon movement of the receptacle, means normally securing the receptacle from. movement relative to the housing and maintaining the same with the switch in off position and being operable upon movement of the plug into cooperating relationship with the receptacle to permit movement of the receptacle to actuate the switch into on position, and means preventing removal of the plug from the receptacle until after the receptacle has been moved back to initial position and the switch actuated to 01f position.

3. In a device of the type described, the combination of a cooperating plug and receptacle, a housing, said receptacle being rotatably mounted in the housing, a switch mountedin the housing, l means cooperable with the receptacle and theswitch to effect actuation of the switch into on and off positions upon rotation of the receptacle, means normally securing the receptacle from rotation and being operable upon movement of the plug into cooperating relationship to the receptacle to permit rotation of the receptacle.

4. In a device of the type described, the combination of a plug and receptacle, a housing, said receptacle being rotatably mounted in said housing, a switch arranged in the housing and being carried by the receptacle and being rotatable therewith, means cooperable withsaid switch and housing to effect actuation of the switch into on and off positions upon rotation of the receptacle and switch, means normally securing the receptacle from rotation and being operable upon movement of the plug into cooperating realtionship to the receptacle to permit rotation of the receptacle and switch.

.. V 5. In a device of the type described, the combination of an enclosed housing provided with a threaded aperture, a receptacle threaded into said aperture, a switch mounted in the housing, motion transmitting means between said receptacle and switch to effect actuation of the switch into on and off positions upon rotation of the receptacle in said aperture, a plug movable into co operating relationship with said receptacle, means normally securing the receptacle against rotation and being operable upon movement of the plug into cooperating relationship to the receptacle to permit rotation of the receptacle.

6. In a device of the type described, the combination of an enclosed housing provided with a threaded aperture, a receptacle threaded into said aperture, a switch arranged in the housing and being carried by the receptacle and being rotatable therewith, a plug cooperable with said receptacle, a latch member carried by the housing and normally engaging said receptacle and retaining the same from rotary movement and being operable upon movement of the plug into cooperative relationship with the receptacle to permit rotation of the receptacle and switch, and means carried by the body and cooperable with said switch to eiiect actuation of the same into on and oii positions upon rotation of the receptacle and switch.

'7. In a device of the type described, the combination of a housing provided with an opening in one side thereof, a closure detachably secured to said opening, a switch mounted in the housing, a receptacle rotatably mounted in the housing and cooperating means to eiTect actuation of the switch into on and off positions upon rotation of said receptacle, means carried by the housing and engaging the closure to prevent removal of the same from the housing, said means being shiftable into engagement with said receptacle when said switch is in the off position and subsequently shiftable out of engagement with said closure to prevent rotation of the receptacle during removal of said closure.

8. In a device of the type described, the combination of a housing provided with an aperture in one side thereof, with said aperture being threaded internally adjacent its inner end, a receptacle provided with external threads and threading into said aperture, a latch member mounted in the outer end of said aperture and normally securing said receptacle from rotary movement, a plug inserta'ble in said aperture'and cooperable with said latch member to move the same out of receptacle-securing position, a switch mounted in the housing, and means cooperating with said receptacle and said switch to actuate the switch into on and ofi positions on rotation 10f said receptacle.

9. In a device of the type described, the combination of a housing formed with a central cylindrical portion and a hub portion extending .radially from said central portion and being provided with an aperture extending therethrough and opening into the central portion, said aperture being provided with internal threads adjacent the inner end, a receptacle threading into said aperture, a latch member pivotally mounted in the outer end of said aperture and being operable to normally secure said receptacle against rotation, a plate secured to the inner end of said receptacle, and a, switch mounted on said plate, a plug insertable in said aperture in cooperating relation to the receptacle and efiecting disengagement of said latch member from the receptacle to permit rotation of the latter, and means carried in the bottom of the cylindrical portion and engaging the operating handle of said switch to prevent movement of the same upon rotary movement of the receptacle and switch.

10. In a device of the class described, the combination of a housing formed with a central portion having an opening in one side, and a hub portion extending radially from said central portion and being provided with an aperture extending therethrough and opening into the central portion, a plug receiving receptacle rotatably mounted in said hub portion, a switch mounted in the cylindrical portion and having its contacts connected to the contacts of said receptacle,

motion transmitting means between said receptacle and switch to effect actuation of the switch into on and off positions upon rotation of the receptacle, a closure for the opening in said cylindrical portion of the housing, and means carried by the body and being cooperable with said closure and receptacle to prevent removal of the closure when the switch is actuated to on position, and being shiftable radially of said receptacle to prevent actuation of the switch into on position during removal of said closure from the housing.

11. In a device of the type described, the combination of a housing formed with a central cylindrical portion having an internally threaded opening in one end thereof, and a hub portion extending radially from said central portion and being formed with an aperture extending therethrough and opening into said central portion, a plug receiving receptacle rotatably mounted in said aperture, a switch mounted in the central portion and having its contacts connected to the contacts of said receptacle, motion transmitting means between said receptacle and switch to effect actuation of the switch into on and off positions upon rotation of the receptacle, a closure threaded into said opening of the central portion of the housing and having a radially extending flange overlying the marginal surface about said opening, a threaded aperture formed in said cylindrical portion and extending from said marginal surface to the aperture in said hub portion, a screw threaded therein and being cooperable with said receptacle when threaded inwardly to secure the same against rotation, and being cooperable with the fiange of said closure when threaded outwardly to secure the closure against rotation.

12. In a device of the type described, the combination of a housing, a receptacle rotatably mounted in the wall of the housing and being arranged to receive a plug at its outer end, a switch arranged in the housing and being secured to the inner end of the receptacle and being rotatable therewith, said switch having an actuating element, means carried by the housing and cooperable with said element to prevent movement of the same during rotation of the switch 

